I've been shooting with EM-1 MkII for around 6 months and have two Olympus batteries for it. Up until recently have been able to take around 150 images on 2 dives and come back with 70% or so battery capacity showing.

Last couple of dives it's gone down to zero capacity with around 60-70 images over two dives. After the first dive where it ran short I marked that battery and the second dive it did similar number of shots on the other battery. After the second dive I tried out the camera at home on the first battery and took 150 frames with normal settings, with plenty of use of AF and normal use of checking the LCD screen. after that I had 88% battery capacity showing. It seems it is not a battery issue as both batteries are doing a similar duty.

The only difference between the dive and the land test is the time taken to take all the frames. I'm using single shot, flash on 1/64 power for all shots and C-AF +TR and manual mode. I have standard settings for sleep and power off. I have theses settings stored under one of the custom settings.

Any suggestions on a setting I may have changed which is constantly draining the battery?

Following up on this topic, I noted the camera would lock up occasionally, leaving a blank screen, but with the backlight still active and the only way to get going again was remove the battery. I ended up upgrading the firmware from 1.4 to the latest and one of the fixes it lists is improved stability while shooting. After upgrading firmware I found battery life wa s back to normal with 70+% showing after 2 dives and 120 plus shots. I'm wondering if one of the fixes also stopped a process that was consuming battery capacity?

This suggests upgrading the firmware is worthwhile. The firmware updater successfully saved all my presets and restored them after upgrading the firmware. Though for some reason the EVF auto switch =off setting did not seem to carry over.